/*
 * $Id: md4.c,v 1.8 2009-03-18 17:48:10 heas Exp $
 *
 * Copyright (c) 1995-1998 by Cisco systems, Inc.
 *
 * Permission to use, copy, modify, and distribute this software for
 * any purpose and without fee is hereby granted, provided that this
 * copyright and permission notice appear on all copies of the
 * software and supporting documentation, the name of Cisco Systems,
 * Inc. not be used in advertising or publicity pertaining to
 * distribution of the program without specific prior permission, and
 * notice be given in supporting documentation that modification,
 * copying and distribution is by permission of Cisco Systems, Inc.
 *
 * Cisco Systems, Inc. makes no representations about the suitability
 * of this software for any purpose.  THIS SOFTWARE IS PROVIDED ``AS
 * IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * md4c.c - RSA Data Security, Inc., MD4 message-digest algorithm
 */

/* Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved.
 *
 * License to copy and use this software is granted provided that it
 * is identified as the "RSA Data Security, Inc. MD4 Message-Digest
 * Algorithm" in all material mentioning or referencing this software
 * or this function.
 *
 * License is also granted to make and use derivative works provided
 * that such works are identified as "derived from the RSA Data
 * Security, Inc. MD4 Message-Digest Algorithm" in all material
 * mentioning or referencing the derived work.
 *
 * RSA Data Security, Inc. makes no representations concerning either
 * the merchantability of this software or the suitability of this
 * software for any particular purpose. It is provided "as is"
 * without express or implied warranty of any kind.
 *
 * These notices must be retained in any copies of any part of this
 * documentation and/or software.
 */

#include <config.h>
#include <string.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#include "md4.h"

#pragma	weak	MD4Final
#pragma	weak	MD4Init
#pragma	weak	MD4Update

typedef unsigned char *POINTER;
typedef uint16_t UINT2;
typedef uint32_t UINT4;

/* Constants for MD4Transform routine. */
#define S11 3
#define S12 7
#define S13 11
#define S14 19
#define S21 3
#define S22 5
#define S23 9
#define S24 13
#define S31 3
#define S32 9
#define S33 11
#define S34 15

static void MD4Transform(UINT4 [4], const unsigned char [64]);
static void Encode(unsigned char *, UINT4 *, unsigned int);
static void Decode(UINT4 *, const unsigned char *, unsigned int);

static unsigned char PADDING[64] = {
  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/* F, G and H are basic MD4 functions. */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG and HH are transformations for rounds 1, 2 and 3 */
/* Rotation is separate from addition to prevent recomputation */
#define FF(a, b, c, d, x, s) { \
    (a) += F ((b), (c), (d)) + (x); \
    (a) = ROTATE_LEFT ((a), (s)); \
  }
#define GG(a, b, c, d, x, s) { \
    (a) += G ((b), (c), (d)) + (x) + (UINT4)0x5a827999; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }
#define HH(a, b, c, d, x, s) { \
    (a) += H ((b), (c), (d)) + (x) + (UINT4)0x6ed9eba1; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }

/* MD4 initialization. Begins an MD4 operation, writing a new context. */
void
MD4Init(MD4_CTX *context)			/* context */
{
    context->count[0] = context->count[1] = 0;

    /* Load magic initialization constants. */
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

/*
 * MD4 block update operation. Continues an MD4 message-digest operation,
 * processing another message block, and updating the context.
 */
void
MD4Update(MD4_CTX *context,			/* context */
	  const unsigned char *input,		/* input block */
	  unsigned int inputLen)		/* length of input block */
{
    unsigned int i, index, partLen;

    /* Compute number of bytes mod 64 */
    index = (unsigned int)((context->count[0] >> 3) & 0x3F);
    /* Update number of bits */
    if ((context->count[0] += ((UINT4)inputLen << 3)) < ((UINT4)inputLen << 3))
	context->count[1]++;
    context->count[1] += ((UINT4)inputLen >> 29);

    partLen = 64 - index;
    /* Transform as many times as possible. */
    if (inputLen >= partLen) {
	memcpy((POINTER) &context->buffer[index], (POINTER)input, partLen);
	MD4Transform(context->state, context->buffer);

	for (i = partLen; i + 63 < inputLen; i += 64)
	    MD4Transform(context->state, &input[i]);

	index = 0;
    } else
	i = 0;

    /* Buffer remaining input */
    memcpy((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
}

/*
 * MD4 finalization. Ends an MD4 message-digest operation, writing the
 * message digest and zeroizing the context.
 */
void
MD4Final(unsigned char digest[16],		/* message digest */
	 MD4_CTX *context)			/* context */
{
    unsigned char bits[8];
    unsigned int index, padLen;

    /* Save number of bits */
    Encode(bits, context->count, 8);

    /* Pad out to 56 mod 64. */
    index = (unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    MD4Update(context, PADDING, padLen);

    /* Append length (before padding) */
    MD4Update(context, bits, 8);
    /* Store state in digest */
    Encode(digest, context->state, 16);

    /* Zeroize sensitive information. */
    memset((POINTER)context, 0, sizeof (*context));
}

/* MD4 basic transformation. Transforms state based on block. */
static void
MD4Transform(UINT4 state[4], const unsigned char block[64])
{
    UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    Decode(x, block, 64);

    /* Round 1 */
    FF (a, b, c, d, x[ 0], S11); /* 1 */
    FF (d, a, b, c, x[ 1], S12); /* 2 */
    FF (c, d, a, b, x[ 2], S13); /* 3 */
    FF (b, c, d, a, x[ 3], S14); /* 4 */
    FF (a, b, c, d, x[ 4], S11); /* 5 */
    FF (d, a, b, c, x[ 5], S12); /* 6 */
    FF (c, d, a, b, x[ 6], S13); /* 7 */
    FF (b, c, d, a, x[ 7], S14); /* 8 */
    FF (a, b, c, d, x[ 8], S11); /* 9 */
    FF (d, a, b, c, x[ 9], S12); /* 10 */
    FF (c, d, a, b, x[10], S13); /* 11 */
    FF (b, c, d, a, x[11], S14); /* 12 */
    FF (a, b, c, d, x[12], S11); /* 13 */
    FF (d, a, b, c, x[13], S12); /* 14 */
    FF (c, d, a, b, x[14], S13); /* 15 */
    FF (b, c, d, a, x[15], S14); /* 16 */

    /* Round 2 */
    GG (a, b, c, d, x[ 0], S21); /* 17 */
    GG (d, a, b, c, x[ 4], S22); /* 18 */
    GG (c, d, a, b, x[ 8], S23); /* 19 */
    GG (b, c, d, a, x[12], S24); /* 20 */
    GG (a, b, c, d, x[ 1], S21); /* 21 */
    GG (d, a, b, c, x[ 5], S22); /* 22 */
    GG (c, d, a, b, x[ 9], S23); /* 23 */
    GG (b, c, d, a, x[13], S24); /* 24 */
    GG (a, b, c, d, x[ 2], S21); /* 25 */
    GG (d, a, b, c, x[ 6], S22); /* 26 */
    GG (c, d, a, b, x[10], S23); /* 27 */
    GG (b, c, d, a, x[14], S24); /* 28 */
    GG (a, b, c, d, x[ 3], S21); /* 29 */
    GG (d, a, b, c, x[ 7], S22); /* 30 */
    GG (c, d, a, b, x[11], S23); /* 31 */
    GG (b, c, d, a, x[15], S24); /* 32 */

    /* Round 3 */
    HH (a, b, c, d, x[ 0], S31); /* 33 */
    HH (d, a, b, c, x[ 8], S32); /* 34 */
    HH (c, d, a, b, x[ 4], S33); /* 35 */
    HH (b, c, d, a, x[12], S34); /* 36 */
    HH (a, b, c, d, x[ 2], S31); /* 37 */
    HH (d, a, b, c, x[10], S32); /* 38 */
    HH (c, d, a, b, x[ 6], S33); /* 39 */
    HH (b, c, d, a, x[14], S34); /* 40 */
    HH (a, b, c, d, x[ 1], S31); /* 41 */
    HH (d, a, b, c, x[ 9], S32); /* 42 */
    HH (c, d, a, b, x[ 5], S33); /* 43 */
    HH (b, c, d, a, x[13], S34); /* 44 */
    HH (a, b, c, d, x[ 3], S31); /* 45 */
    HH (d, a, b, c, x[11], S32); /* 46 */
    HH (c, d, a, b, x[ 7], S33); /* 47 */
    HH (b, c, d, a, x[15], S34); /* 48 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    /* Zeroize sensitive information. */
    memset((POINTER)x, 0, sizeof (x));
}

/*
 * Encodes input (UINT4) into output (unsigned char). Assumes len is a
 * multiple of 4.
 */
static void
Encode(unsigned char *output, UINT4 *input, unsigned int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4) {
	output[j] = (unsigned char)(input[i] & 0xff);
	output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
	output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
	output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
    }
}

/*
 * Decodes input (unsigned char) into output (UINT4). Assumes len is a
 * multiple of 4.
 */
static void
Decode(UINT4 *output, const unsigned char *input, unsigned int len)
{
    unsigned int i, j;

    for (i = 0, j = 0; j < len; i++, j += 4)
	output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
		(((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}
